This invention relates to a new process for achieving nucleophilic substitution reactions on unactivated aromatic rings bearing appropriate leaving groups. The invention further relates to such substitution reactions by anionic nucleophiles under catalysis by a cyclic or acyclic polydentate chelating ligand.
Substituted aromatic compounds comprise a vast segment of organic chemistry. Their importance as products and intermediates ranges across the entire field of chemical manufacturing activity. Novel means for preparing substituted aromatic compounds which involve lower costs for energy, raw materials, and processing will have significant beneficial economic impact in wide areas of the chemical processing industry. In particular, improved processes for manufacture of aromatic derivatives with herbicidal and other biochemical activity offer possibilities for improved performance in production of food grains and other crops.
Few examples of nucleophilic substitutions of unactivated aromatic substrates are reported in the literature. Chemical experience clearly shows that in cases where a potential leaving group on an aromatic ring is not activated in some way, the attack of reagents that donate an electron pair in chemical reactions, i.e., nucleophiles, does not occur or is very sluggish.
In cases where such reactions are performed, they typically involve special solvents, or unusual catalysts, or forcing conditions of high temperature, or all of these. Often, the application of such extreme conditions leads to molecular rearrangements of the substrates and to mixtures of products.